Hi all- This adds a new "xonly" mode for vsyscalls and makes it the default. xonly is a bit more secure -- Kees knows about an exploit that relied on read access to the vsyscall page. It's also nicer from a paging perspective, as it doesn't require user access to any of the kernel address space as far as the CPU is concerned. This would, for example, allow a much simpler implementation of per-process vsyscall disabling.
Andy Lutomirski (5): x86/vsyscall: Remove the vsyscall=native documentation x86/vsyscall: Add a new vsyscall=xonly mode x86/vsyscall: Document odd #PF's error code for vsyscalls selftests/x86/vsyscall: Verify that vsyscall=none blocks execution x86/vsyscall: Change the default vsyscall mode to xonly .../admin-guide/kernel-parameters.txt | 11 ++- arch/x86/Kconfig | 32 ++++--- arch/x86/entry/vsyscall/vsyscall_64.c | 19 ++++- arch/x86/mm/fault.c | 7 ++ tools/testing/selftests/x86/test_vsyscall.c | 83 +++++++++++++------ 5 files changed, 107 insertions(+), 45 deletions(-) -- 2.21.0
